I found this word in a paper written by one of my great aunts. She was an art student in London in the 1920s and her papers included many life studies and designs for fabrics. The designs had a marked art-deco flavour as I guess you would expect. She also had a penchant for sketching film-stars, I would think copied from ‘photos, but they seem good to my untutored eye.

Du"pi*on (?), n. [F. doupion, It. doppione, fr. doppio double, L. duplus. See Double, and cf. Doubloon.] A double cocoon, made by two silkworms. A rough silk fabric made from the threads of such cocoons.

“Dupioni (sometimes spelled 'douppioni' or 'dupion'), is a lustrous silk often woven from two different colors of threads, so that it shimmers or changes color in the light. Dupioni is made from an irregular, rough silk reeled from double cocoons or cocoons spun side-by-side which are interlocked, making it necessary to reel them together. Usually brightly colored, it has a moderately crisp drape, fairly reflective luster, and a nubby texture. It is crisp to the touch and doesn't wrinkle badly or hold a crease well. It is reversible, not particularly stretchy, and relatively easy to sew.”

I can’t see how the two threads can be dyed different colours if they are interlocked. Trick o’ the trade no doubt. But then I don’t know much about silk manufacture, can anyone explain further?